This invention concerns providing a sanitary napkin which is so constructed as to incorporate a fluid distributing channel impressed into the absorbent element of the napkin and is provided with a cover for the body facing side which cover remains clean and dry after deposition of body fluid thereon. In particular, this invention relates to a sanitary napkin so constructed as to fully utilize the fluid distribution properties of a channel without sacrificing the clean and dry attributes of the cover.
For many years sanitary napkins have comprised a loosely associated pad or batt of absorbent fibers such as wood pulp or rayon, of generally uniform density, enveloped in a body fluid permeable cover and provided, on the garment side thereof, with a fluid impermeable barrier layer. While such napkins have functioned more or less satisfactorily, it has been long recognized that the uniform density pad does not allow for full utilization of the absorption capacity of the pad and instead the napkins tend to fail, i.e., leak body fluids onto the outer garment facing surfaces, before the pad is fully saturated.
Recent prior suggestions have been made to obviate this problem, typical of which is that disclosed in U.S. Pat. No. 4,184,498 issued to Pierre Franco on Jan. 22, 1980. As disclosed therein, a pad is provided with a densified longitudinally extending centrally positioned channel impressed into the body facing side and surrounded by less dense peripheral portions of the pad. The central channel serves to direct fluid deposited centrally on the pad in a generally longitudinal direction and thereby make better use of the absorbent capacity of the pad. In commonly assigned U.S. Ser. No. 530,320 filed on Sept. 8, 1983 a similarly channeled pad for a sanitary napkin is disclosed which pad is provided with a density gradient with the density varying from a low density in a central portion of the pad to a rapidly increasing high density at the extreme peripheral portions of the pad. This described density pattern again provides improved fluid transport to more fully utilize the absorbent capacity of the pad.
In addition to the problem of fluid transport, the art has recently been concerned with the desirable feature of providing a cover for a sanitary napkin which, after deposition of body fluid, is capable of maintaining a clean and dry appearance. Accordingly, sheet materials for use as the cover or facing for sanitary napkins have been selected to be not only pervious to body fluid but also not wettable by such fluid, i.e., hydrophobic. Such hydrophobic facing materials have several advantages in that they remain relatively dry and hence more comfortable in use. Additionally, by not wetting they remain free of stain on their exterior surface. The art is now replete with suggestions for utilizing hydrophobic facings in body fluid absorbent products. For example, in U.S. Pat. Nos. 3,695,269; 4,041,951; and 4,391,869; it has been suggested that nonwoven fabrics comprised of hydrophobic fibers be employed as the facing in absorbent products. In U.S. Pat. Nos. 2,992,644; 3,814,101; and 4,324,246; it is suggested that the facing comprise a continuous sheet of hydrophobic polymeric material rendered permeable to body fluid by being provided with apertures.
In a commonly assigned U.S. patent application filed on this day bearing Ser. No. 632,753, a particularly useful facing is suggested, which is not only substantially nonwettable and fluid pervious but which also greatly enhances the clean and dry appearance of the product after it has absorbed body fluids. This facing comprises a continuous sheet of a polyolefin incorporating therein from 5 to 12 percent by weight of titanium dioxide and having apertures therethrough for the passage of body fluid. The open area of the apertures comprise from 1.3 to 35 percent of the total area intended for the passage of body fluids. The combination of prescribed open area and titanium dioxide content results in a facing which allows for the passage of fluids, remains dry, and moreover, appears clean and dry by masking the stain pattern on the underlying absorbent pad.
It can thus be seen that solutions have been presented for improving fluid transport in a pad and that solutions have been presented for providing a cover with a clean and dry appearance. Unfortunately, it has been discovered that when attempting to employ the suggested solutions to the two problems, (i.e., fluid transport and clean and dry appearance) in a single pad, unsatisfactory results are obtained. Specifically, when a cover such as that described in connection with above-referenced application, Ser. No. 632,753, is employed on a pad without a central channel, excellent clean and dry properties follow. On the other hand, when employing such a cover on a channeled product, while the majority of the body facing surface of the cover remains clean and dry and appears so to the user, the portion of the cover overlying the channel retains a small but measurable, apparent and undesirable quantity of body fluid.
Accordingly, there is a need to provide a napkin capable of combining the clean and dry aspects of a cover having such properties with the fluid transport properties of a channeled pad.